It's been shown here you can BUY Alexa Numbers, that's why Ortsbo won't comment on them.  INT relies on Google Analytics and 3rd Party Bankable verification of Unique Users.

 

I used to use Alexa numbers only to spot a change in trends, as they are updated constantly, but Ortsbo has too many websites now for them to be reliable indicators, unless you check all Ortsbo's websites.